Transient orcas are one of three varieties of orca communities found along the coast of British Columbia. What sets them apart from the well known fish eating resident orcas is that transients prey on marine mammals. They are more difficult to study because they live in smaller groups, usually consisting of 2-6 individuals, and they cover a large area in search of prey, continuously on the move to maintain their stealth tactic of hunting. If they stayed in the same area for a prolonged amount of time, its prey would be alerted to its presence, thus reducing successful hunting. With this on-the-move lifestyle, they can easily travel over 100km a day.
The range of transient orcas on the west coast of North America stretches from southern California to the Aleutian Islands of Alaska. All transient orcas share a common set of vocal signals, with some small varieties existing, but because of transient’s fluid social order, they have not developed the unique calls/dialects, like resident orcas. Transients also tend to be vocally/acoustically quiet most of the time. They tend to use passive sonar, listening for the sounds of their prey, such as a splash from a swimming seal or a whistle from a dolphin. This is part of the transient orca’s stealth hunting style/tactic. If they were vocal while hunting, it could alert their prey to their presence. Transients can be quite vocal when socializing, especially after a successful hunt.
They prey on a number of marine mammals, most commonly harbour seals, but also consists of harbour porpoise, Dall’s porpoise, Pacific white sided dolphins, gray whales, minke whales and Stellar sea lions. Seabirds are also attacked, but not usually eaten. Many times young/juvenile orca are seen “playing” with seabirds, which might be an important tool/means of practicing hunting skills/techniques. Transient orcas have also been observed preying upon deer/moose that sometimes swim between islands.
There is much more to be learned about transient orcas, but they are more difficult to study than resident orcas. They tend to be hard to find and easy to lose, but as more research is undertaken throughout their known range, our knowledge and understanding of these enigmatic creatures will continue to grow.